Cognitive impairment and dementia are common after stroke. However, the criteria with which to describe and categorize stroke patients with vascular cognitive impairment (VCI) are not clear. Previous diagnostic systems have relied upon consensus criteria for conditions such as vascular dementia, but this has led to inconsistencies in the prevalence rate of the condition and the sensitivity and specificity of the criteria, depending upon which diagnostic system is used. Instead of consensus criteria, there is now a call for data- driven diagnostic systems. In April 2005, NINDS and the Canadian Stroke Network co-sponsored a Harmonization Workshop in Washington DC to foster multi-center collaboration and communication in the VCI community by developing standard protocols in the areas of neuropsychology, neuroimaging, epidemiology, pathology, and experimental research. It is hoped that use of these standard protocols will lead to the multi-site, collaborative study of VCI that is necessary to establish diagnostic criteria, examine underlying mechanisms, such as genetic factors, and promote treatment research. As part of the workshop, the Neuropsychology Working Group established three neuropsychology protocols, defined by the length of time necessary to complete them: a 60 Minute Protocol, a 30 Minute Protocol and a Five Minute Protocol. The aim of this project is to test the reliability and validity of these protocols in a multi-center sample of 100 ischemic stroke patients and 100 demographically matched controls. An integral part of the project is to assess the concurrent validity of the neuropsychology test protocols by examining their relationship to known neuroimaging factors, such as the size and location of stroke lesions and subcortical hyperintensities and the extent of cerebral atrophic changes. In addition, the project will explore relationships between the neuropsychology test protocols and both thalamic volumes and diffusion tensor indices, such as fractional anisotropy. Reliable and valid VCI neuropsychology test protocols are a necessary first step to improved diagnostic criteria and a better understanding of both the mechanisms of VCI and the development of new treatment options.